processing_node.h - mozsearch

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/*

Copyright 2018 Google Inc. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");

you may not use this file except in compliance with the License.

You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software

distributed under the License is distributed on an "AS-IS" BASIS,

WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

See the License for the specific language governing permissions and

limitations under the License.

*/

#ifndef RESONANCE_AUDIO_NODE_PROCESSING_NODE_H_

#define RESONANCE_AUDIO_NODE_PROCESSING_NODE_H_

#include <memory>

#include <vector>

#include "base/audio_buffer.h"

#include "node/publisher_node.h"

#include "node/subscriber_node.h"

namespace vraudio {

// Audio processing node that reads from multiple inputs, processes the

// received data and outputs its result.

class ProcessingNode : public Node,

                       public SubscriberNode<const AudioBuffer*>,

                       public PublisherNode<const AudioBuffer*> {

 public:

  typedef SubscriberNode<const AudioBuffer*> SubscriberNodeType;

  typedef PublisherNode<const AudioBuffer*> PublisherNodeType;

  // Helper class to manage incoming |AudioBuffer|s.

  class NodeInput {

   public:

    // Constructor.

//

    // @param input_vector Vector containing pointers to incoming

    //     |AudioBuffer|s.

    explicit NodeInput(const std::vector<const AudioBuffer*>& input_vector);

    // Returns a nullptr if zero or more than one input buffers are available.

    // Otherwise a pointer to the single input |AudioBuffer| is returned. This

    // method should be used if only a single input |AudioBuffer| is expected.

//

    // @return Pointer to single input |AudioBuffer|.

    const AudioBuffer* GetSingleInput() const;

    // Returns vector with input |AudioBuffer|s.

//

    // @return Pointer to single input |AudioBuffer|.

    const std::vector<const AudioBuffer*>& GetInputBuffers() const;

    // Delete copy constructor.

    NodeInput(const NodeInput& that) = delete;

   private:

    // Const reference to vector of input |AudioBuffer|s.

    const std::vector<const AudioBuffer*>& input_vector_;

};

  ProcessingNode();

  // SubscriberNode<InputType> implementation.

  void Connect(

      const std::shared_ptr<PublisherNodeType>& publisher_node) override;

  // Node implementation.

  void Process() final;

  bool CleanUp() override;

  // By default, calls to AudioProcess() are skipped in case of empty input

  // buffers. This enables this node to process audio buffers in the absence of

  // input data (which is needed for instance for a reverberation effect).

  void EnableProcessOnEmptyInput(bool enable);

  // Disable copy constructor.

  ProcessingNode(const ProcessingNode& that) = delete;

 protected:

  // Calls |CleanUp| on all connected input nodes.

  void CallCleanUpOnInputNodes();

  // Pure virtual method to implement the audio processing method. This method

  // receives a vector of all input arguments to be processed and requires to

  // output a single output buffer.

//

  // @param input Input instance to receive pointers to input |AudioBuffer|s.

  // @return Returns output data.

  virtual const AudioBuffer* AudioProcess(const NodeInput& input) = 0;

 private:

  // PublisherNode<OutputType> implementation.

  std::shared_ptr<Node> GetSharedNodePtr() final;

  Node::Output<const AudioBuffer*>* GetOutput() final;

  // Input stream to poll for incoming data.

  Node::Input<const AudioBuffer*> input_stream_;

  // Output stream to write processed data to.

  Node::Output<const AudioBuffer*> output_stream_;

  // Flag that indicates if |AudioProcess| should be called in case no input

  // data is available.

  bool process_on_no_input_;

};

}  // namespace vraudio

#endif  // RESONANCE_AUDIO_NODE_PROCESSING_NODE_H_